i didn't have a restore cd, so i downloaded a live cd of ubuntu, got on there and managed to remove the registries that were causing my updating issues. so if it comes to that and you dont have a windows cd you have a way out. its just a lot harder. but your problem isnt updating java, your also not asking how to remove it, as for the verification of that i dont think that is normally there, and I dont believe its of java origin.
Not sure about these forum rules when it comes to links. but here is a interesting link to microsoft on the problem.
unknown uneditable registry entry at 'microsoft\DbgagD\1' address-is the registry corrupt?